1. Field of the Invention
The present invention relates to a receiver, and more specifically to a receiver that receives and decodes a signal transmitted by radio, and to a receiving method of the receiver.
2. Description of the Related Art
Such a receiver includes a mixer that converts a radio frequency (RF) signal received by an antenna into a signal in an intermediate frequency (IF) band. The mixer mixes an amplification signal of the RF signal with a local oscillation signal generated by a local oscillation circuit, to generate the intermediate frequency signal in the IF band.
It is desired that receivers contained in cellular phones, movable transceivers, and the like driven by batteries have reduced power requirements to allow a long period of use. Thus, for the purpose of reducing the power requirements, there has been proposed a receiver in which an operation current of a voltage controlled oscillator (VCO) contained in a local oscillation circuit is controlled on the basis of a difference value between signals before and after passing a low-pass filter for removing a noise component, which corresponds to interfering waves contained in a received signal, in other words, on the basis of the levels of the interfering waves (for example, see Japanese Patent Application Laid-Open No. 2007-81708).
However, in the receiver described above, when the interfering waves are at high levels, the operation current of the VCO increases and thus it is difficult to significantly reduce electric power consumption.